Distribution of European yew (Taxus baccata L.) in the "Cisy nad Liswartą" reserve

Abstract

The study analyses the spatial distribution of European yew and its co−occurrence with other trees or different individuals of the species. The study was conducted in the ‘Cisy nad Liswartą' nature reserve (50°46'27.12"N, 18°47'11.86"E). Data was collected in the whole reserve as well as on three 40×40 m study plots. The selected plots varied in terms of yew density, stand species composition and soil humidity. Study plots were divided into 16 squares (10×10 m). Ripley's K functions were used to examine spatial patterns of yew and other tree species populations. The distribution of all trees was random in the reserve. However, distribution of yew population was clumped. Yew preferred sites close to the creeks. Significant clustering of yew trees at distances up to 60−180 m was found. Distribution of yew on plot II was random, while clumped on plots I and III. The co−occurrence of yew and other tree species was random on plot I. Nevertheless, the positive correlation was found for yew and other tree species at the scale of 13−19 m and negative correlation at the distance 0−4 m. Co−occurrence of yew and other tree species was random on plot III as well. Negative correlation was found for thin yew and spruce at the distance of 8 m on plot I. Positive correlations were noticed for yew and other tree species, yew and sycamore at the distance 16 m on plot II. Negative correlations at the distance 18 m were achieved on plot III for: yew and alder, large yew and alder, yew and other tree species of diameter 15−35 cm. Yew grows on higher places, on small islands. The competition between spruce and yew (negative correlation) was the consequence of light and humidity demand of both tree species. The negative correlation between yews and medium alders on longer distance was the result of light competition